Laminated core for electric generators and motors.



H. H. 'WAHf. LAMINATED CORE FOB ELECTRIC GENERATORS AND MOTORS.

APPLICATION FILED DEC.

Patented Dec; 9, 1913.

UNITED s'rA'rEs PATENT orricsl HENBY H. WAIT, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO BAA-BEAU BATTU SMOOT COMPANY, A CORPORATION OF NE! YORK.

LAMINATED CORE FOR ELECTRIC GENERATORS AND MOTORS.

Specification of Letters Patent.

Pal out ed Doc. 9, 1913.

Application filed December 7, 1908. Serial No. 348,692.

To all whom it may concern:

Be it known that l, Hnxnr ll. \Virr, cili- Zen of the United States, residing at hicago, in the county of (lee-l: and State of Illinois, have invented a certain new and useful Improvement in Laminated (.orcs

for Electric Generators and Motors. of which the following is a tull; clc1r. concise,

and exact description.

My invention relates to electric generators and motors, and has for its object to increase the etliciency and capacity of such inachii'ies by providing improved means for carrying away the heat generated in the cores thereof.

In the rotating fielttruagnct of an alternator, this heat comes almost entirely from the heating effect of the current flowing in the conductors; while in rotating armature; it comes partly from thc conductor-\- and partly from the hysteresis and eddy currents in the body of the core and in the teeth. lt has been customary to accomplish the cool ing of such cores by providing ventilating space in the interior coninnmii-ating with ll radial passages, whereby a circulation of a is caused when the core rotated. In high-- speed machines, such as tlnstdrii'cn by steam turbines, the allowable peripheral speed limits the diameter of the rotor to a. small dimension, compared to its length and to the size of shaft rcipiired: and where the rotary member of such machines is an armature having a changing i'nagnclic flux, the frequency of: such change is very high, caus ing a very great loss by hysteresis and eddy currents per unit of volume of the core. in such cases, it will be seen that not. only are the possibilities for ventilati n reduced. but. the causes which necessitate provision l'or carrying oil the heat are incri'liscd.

The pres. nt invention otter. a incuns l' r radiating the heat generated at the surface of the cor either with or without the assistance ol' th usual ventilating passages.

Gen lily speaking, the invention consists in building up the core of laniinalions in such manner that at frequent intervals along the core, the odg :s of certain of the laminae project beyond the edges of adjacent laminae, forming a. large number oi raise-:1 flanges or annular ribs which thus piovidc a greatly increased radiating surface for the core.

A feature of the invention consists in inalijug such projecting laminae or plates of non magnetic metal of high hcatconductivity,

such as hard copper bronze. or manganese steel, so that the increased radiating surface may he obtained without increasing the selfinduction of the armature; and another feature consists in the projecting portions being angularly inclined with reference to the dirt-ction of movement. so that they Will. act as fan blades to maintain a current of air along the core.

I will dcscriltac my invention more particularly by reference to the accompanying drawings, in which- Figure l a lrmgitinlinal sectional view of a dynamo armature, such as may be used for a. high speed turbine-driven generator, i-onstructc l in accordance with my invention; Fig. 2 is a detailed View taken crosswise of the armature, showingone of the annular projecting copper plates surrounding and confining the electrical conductors in the armature slots: Figs. 3 and 4 illustratc dill'crent groupings or dispositions of the projecting laminae. Figs. 5 and G illustrate now the projecting portions of the teeth may he angularly inclined to serve as fan blades: Fig. 7 is an enlarged detail view in longitudinal section illustrating the prefe red tor-m shown in Fig. 1 in which annular plates or lan'iinae of hard copper, interspersed at frequent. intervals between the iron laminations and projecting beyond. the outer surface of the core, extend only part way into the core, the central portions or disks within such annular copper plates being of ironto increase the magnetic conductivity in the interior of the core; 'Fig'. 8 is a detail View of a modification showing a portion of the armature 4, in cross-section, looking at the face of one of the laminae.

liikc parts are designated by similar lettors of reference throughout the several views.

The armature core shown in Fig. 1 is composed of iron disks or luminations a assembled upon a shaft 1), heavy iron cheek plates being rovided at. the ends to hold the body of laminations together. As shown most clearly in Fig 2-, the periphery of the core may be slotted longitudinally, and the copper conductors c c of the armature winding are embedded in these slots in the usual man-.

The laminations of the core are wholly or partly iron disks of different diameters disposed in such a way that the edges of certam lamina? a a at frequent intervals along the core, project radially beyond the edges of adjacent laminae, forming a large numher of annular flanges or ribs around the core and thereby greatly increasing the heatradiating surface. These projecting laminae a may be arranged singly, as in Fig. 4, or in groups, as in Fig. 3. These rojections revolve at a high peri heral speed and consequently'are very e ective in dissipating the heat from the core. In Figs. 5 and 6, the projecting teeth are shown inclined to the direction of motion, so as to act as fan blades and maintain a draft of air longitudinally along the surface of the cord.

In continuous current machines, the projecting teeth a if of iron will add considerably to the self-induction of the windings. In machines having commutating poles, this increased self-induction maybe com ensated for, but in ordinary types of mac ines, it may be objectionable. This objection however, can be obviated by making the projecting disks of hard copper, bronze, manganese steel, or other non-magnetic metal wlnch will'be of high conductivity without contributing to the self-induction of the armature. In Figs. 1 and 7, the projecting laminae a are of such non-magnetic metal and extend only part way into the core, the space at the center, within each annular nonmagnetic lamina, being occupied by a smaller concentric disk of iron. By such a construction, the magnetic conductivity of the armature as a whole is not seriously impaired, while the sclf-induction at the surface is kept low.

In commutating machines running at high speeds, where it is desired to avoid self induction, and yet have the slots closed at the top, the bronze disks can be made to surround the coils and serve to retain them, while the slots in the iron can be left wholly or partially open at the top. The conductors will be threaded throu h the holes in the bronze disks. Such pre erred construction is indicated in Fig. 2.

While I have illustrated my invention as applied to a direct-current dynamo armature, it will be apparent that it is not limited to such application, but will be useful in the construction of the rotors of alternating-current machines; and may even be applied to the stator, in which case the circulation of air is caused by the windage from the rotor.

It will be noted that when a core constructed with circumferential heat-radiating ridges as above described is put into rotation relatively to the surrounding air, the heat dissipated by said ridges is carried off by a construction of dynamo armatures previ-- ously devised by me, in which the tops of most of the teeth at the periphery of the armature are cut down to decrease the selfinduction, leaving only a few teeth with ends overhanging the slot at two or three places along the length of the core to hold the conductors in place in the slot. In the present invention, which is for a widely different purpose, all the iron teeth are complete, and many of the lamina: at fre uent intervals along the core project beyon adjacent laminae, forming. a large number of heat radiating flanges or ribs at the expense of deliberately increasingthe self-induction. unless the projectin lamina: be

made of non-magnetic materia as one form and a winding on said core, said copper plates projecting beyond the exterior surface of the core and its windings so as to form salient flanges adapted to dissipate heat.

2. A core for electric machines, built up of iron laminations, and lates of non-magnetic metal interspersed etween said iron laminations, said core having slots receiving electric conductors, said non-magnetic (plates extending over said slots to retain sai conductors in place, and projecting beyond the iron laminations to form heat-radiating flanges.

3. A tors and motors, built up of iron animations, interspersed with annular non-magnetic laminations, projecting radially be yond the iron, but extending only part way mto the bod of the core, the inner space circumscribe by said annular non-magnetic laminations being filled by concentric disks of iron; whereby a large heat radiating surface is secured without unduly increasing the self-induction of the armature or impairing the magnetic conductivity of the core.

In witness whereof, I hereunto subscribe my name this 5th day of December A. D., 1906.

HENRY H. WAIT.

core for the rotors of electric en'erw. 

